Ogawa Tadashi, Mori Hirotada, Tomita Masaru, Yoshino Masataka
Department of Biochemistry, Aichi Medical University School of Medicine, Nagakute, Aichi 480-1195, Japan.
Res Microbiol. 2007 Mar;158(2):159-63. doi: 10.1016/j.resmic.2006.11.003. Epub 2006 Dec 20.
For analyzing the control of energy metabolism in Escherichia coli, we carried out kinetic analyses of glycolytic enzymes purified from the overexpressing clones of E. coli K12 W3110 that were constructed with the vector pCA24N. Phosphoenolpyruvate (PEP) acted as an effective inhibitor of enzymes of the preparatory phase in glycolysis. Glucokinase was potently inhibited by PEP in a competitive manner with respect to ATP: the K(i) value for PEP was 0.1mM. PEP further inhibited phosphoglucoisomerase to a lesser extent, and phosphofructokinase A and aldolase A with 10-fold the K(i) values of glucokinase and phosphoglucoisomerase. Glucose is incorporated into E. coli through two pathways: the PTS (PEP-dependent phosphotransferase system) and the glucokinase reaction. PEP, a potent inhibitor of E. coli glucokinase, unlike most eukaryotic hexokinases, can act as a signal molecule controlling glucose uptake and glycolytic flux in cells.
为了分析大肠杆菌中能量代谢的调控，我们对从用载体pCA24N构建的大肠杆菌K12 W3110过表达克隆中纯化的糖酵解酶进行了动力学分析。磷酸烯醇式丙酮酸（PEP）作为糖酵解准备阶段酶的有效抑制剂。葡萄糖激酶被PEP以与ATP竞争的方式强烈抑制：PEP的K(i)值为0.1mM。PEP对磷酸葡萄糖异构酶的抑制作用较小，对磷酸果糖激酶A和醛缩酶A的抑制作用，其K(i)值是葡萄糖激酶和磷酸葡萄糖异构酶的10倍。葡萄糖通过两条途径进入大肠杆菌：磷酸烯醇式丙酮酸依赖的磷酸转移酶系统（PTS）和葡萄糖激酶反应。与大多数真核己糖激酶不同，PEP是大肠杆菌葡萄糖激酶的有效抑制剂，它可以作为控制细胞中葡萄糖摄取和糖酵解通量的信号分子。
